1. Field of the Invention
This invention relates generally to protective corner guards for pages or book covers, especially thin flexible book covers such as is used on paperback books, and more particularly to an improved corner guard configured to allow opposing pages or book covers to slide easily over the guard without catching on its edges, while also helping the protected corner from becoming creased, torn or weakened.
2. Description of Related Art
Many documents, both bound and unbound, include a cover constructed from paper, cardboard, leather or the like that is designed to protect the enclosed sheets of the document. Unfortunately, covers are themselves susceptible to gradual wear and progressive damage, and once a cover becomes significantly damaged, the enclosed pages are left with less protection and are thus more subject to damage. Invention and use of complete document covers are well known to the public, as there is a wide variety of different paper, plastic and cloth covers available to protect the entire document cover. However, these cover protectors are generally bulky, inconvenient and difficult to properly position over a book cover. In addition, they obscure a book cover and its design.
The corners of a document are typically the most susceptible to being bent or torn, which is particularly undesirable since corner damage makes it difficult to easily and quickly turn the pages of the document. Thus, invention and use of protection devices designed expressly to protect page and book corners is well known to the public. Corner protectors are much more light weight and non-obtrusive than full page covers designed to cover the entire document cover.
Prior art corner protectors have typically been constructed with one of two different basic configurations. The most common configuration consists essentially of a triangular strip of heavy duty paper, cardboard or metal that fits across the outer surface of a corner providing an edge that is at approximately a 45.degree. angle to the edges of the page or book cover.
For example, Leander U.S. Pat. No. 2,728,451 discloses a corner protector that is the shape of a right triangle. A perforation is positioned along the height of the triangle, thereby effectively dividing the protector into two smaller right triangles. To position the protector over the corner, one of the two smaller triangles is placed over the front side of a corner so that the right angle of the protector is aligned with the right angle of the corner and the perforation is aligned with one of the edges of the paper. The protector is then simply folded along the perforation so that the other of the two triangles covers the back side of the corner in the same manner.
Moskowitz U.S. Pat. No. 1,676,741 discloses a corner protector that is formed of two pieces of triangular metal. The two pieces are of identical size and shape and are designed to be engaged with a beaded clamping means. Thus, to protect a corner, one piece of metal is aligned with the back of the corner and the other piece is aligned with the front of the corner and the two pieces are then clamped together.
Wright et al. U.S. Pat. No. 536,315, Akins U.S. Pat. No. 295,141 and Martin U.S. Pat. No. 318,486 all disclose similar corner protecting means in which the protector covers the front side of the corner at a 45.degree. angle. These protectors differ only in their specific methods of folding and application.
While corner covers with this 45.degree. structure may effectively protect the underlying portion of the corner from excessive damage, the protectors themselves often damage the corner. Damage occurs because, with the corner guard in place, the reinforced corner does not tend to bend and flex naturally, but instead always creases sharply along the edge of the guard. Thus, a large, permanent crease gradually forms in the corner along the edge of the guard, which, over time, may actually cause the protected corner to be severed from the rest of the cover.
The other major corner protector configuration is essentially L-shaped, with an elongate strip of material aligned with each of the edges of the corner. This type of protector is illustrated in both Milton U.S. Pat. No. 1,773,742 and Weaver U.S. Pat. No. 308,718. Although this configuration appears to improve over the previously described protectors in that it does not cut directly across the corner with a straight edge, it still causes the corner to bend in a linear path. With the L-shaped design this creasing occurs because the terminal ends of the protector become pressure points onto which the forward force generated while turning the corner is transferred. This pressure is then transferred from each of the pressure points directly across the corner, thus causing a linear crease to form in the cover along an imaginary line interconnecting the ends of the protector. In addition, L-shape protector covers and protects only the outermost edges of the corners, thus leaving a much larger surface area uncovered than the prior art employing the 45.degree. design. In addition, the exposed portion of the corner along the edge of the L-shaped protectors is generally very weak and susceptible to puncture.
Even further, all of these prior art devices provide sharp, pointed edges and corners, and are thus prone to easily catching on items such as a page or cover of a book, or a fingernail, etc. This is obviously undesirable, and may result not only in scraping or scratching the particular item, but also in tearing or premature wearing of the corner guard itself.
Thus there is a significant need for an improved corner protector that can overcome all of the disadvantages of the prior art. Unlike the prior art, such a corner would not cause a linear crease to form in the corner of the cover.
The present invention fulfills these needs and provides further related advantages as described in the following summary.